Facets
A facet is essentially a file purpose classification label. It is defined by ClearlyDefined as:
A facet of a component is a subset of the files related to the component. It’s really just a grouping that helps us understand the shape of the project. Each facet is described by a set of glob expressions, essentially wildcard patterns that are matched against file names.
Each facet definition can have zero or more glob expressions. A file can be captured by more than one facet. Any file found but not captured by a defined facet is automatically assigned to the core facet.
coreThe files that go into making the release of the component. Note that the core facet is not explicitly defined. Rather, it is made up of whatever is not in any other facet. So, by default, all files are in the core facet unless otherwise specified.
dataThe files included in any data distribution of the component.
devFiles primarily used at development time (e.g., build utilities) and not distributed with the component
docsDocumentation files. Docs may be included with the executable component or separately or not at all.
examplesLike docs, examples may be included in the main component release or separately.
testsTest files may include code, data and other artifacts.